Evolution of a degradative bacterial consortium during the enrichment of naphtha solvent

A microbial mixed culture able to degrade naphtha solvent, a model of hydro carbon aromatic mixture, was isolated from a hydrocarbon-polluted soil. Com position of the population was monitored by phenotypic and molecular method s applied on soil DNA, on whole enrichment culture DNA, and on 85 isolated strains. Strains were characterized for their 16S rDNA restriction profiles and for their random amplified polymorphic DNA profiles. Catabolic capabil ities were monitored by phenotypic traits and by PCR assays for the presenc e of the catabolic genes methyl mono-oxygenase ( xylA,M), catechol 2,3 diox ygenase (xylE) and toluene dioxygenase (todC1) of TOL and TOD pathways. Dif ferent haplotypes belonging to Pseudomonas putida, Ps. aureofaciens and Ps. aeruginosa were found to degrade aromatic compounds and naphtha solvent. T he intrinsic catabolic activity of the microbial population of the polluted site was detected by PCR amplification of the xylE gene directly from soil DNA.